Wireless communication systems have been extremely popular for more than a decade. They allow users to communicate with each other while remaining geographically mobile. In addition, these systems allow communications to be in different modes, such as full-duplex voice, half-duplex voice, and data, as examples. These systems also employ a plurality of base transceiver stations (BTS) to transmit and receive information to and from subscriber units (SU) via a wireless medium.
Generally, base transceiver stations (BTS) are able to transmit and receive information using different antenna modes. For example, some base transceiver stations (BTS) may be configured to transmit and receive information in single-input and single-output (SISO), multiple-input multiple-output (MIMO), and beamforming antenna modes. It shall be understood that there are other antenna modes, including multiple-input single-output (MISO), single-input multiple-output (SIMO), and others.
In SISO mode, there is a single antenna at a base transceiver station (BTS) that transmits and receives signals to and from and a single antenna at each subscriber unit (SU). The SISO mode is generally the simplest to implement, but may be susceptible to many radio frequency (RF) environment problems, such as fading, multipath interference, and others.
In MIMO mode, there are multiple antennas at a base transceiver station (BTS) that transmit and receive signals to and from and one or more antennas at each subscriber unit (SU). The MIMO mode, although generally more complex than SISO, may provide improved performance because it is typically better at reducing the effects of many RF environment problems, such as fading, multipath interference, and others.
In beamforming mode, an antenna present at a base transceiver station (BTS) is excited in a particular fashion implement and control the directivity of the antenna. Beamforming allows the antenna to focus more of its output energy in a particular direction for improved transmission to subscriber units (SU). Additionally, beamforming also sensitizes the antenna in a particular direction for improved reception of signals from subscriber units (SU). In certain situations, beamforming may provide improved performance over MIMO.
In view of the various antenna modes and their respective advantages, it would be desirable to provide a base transceiver station (BTS) with the capability of changing antenna modes to better suite the current state of the RF environment. However, employing multiple antennas and associated equipment at base transceiver stations (BTS) to generate the respective different antenna modes would generally be relatively expensive and costly to maintain.